from math import hypot

a, b, c, d = map(float, input().split())
e = hypot((a-c), (b-d))
print(e) from math import hypot a, b, c, d = map(float, input().split()) a map(float, input().split()) map float input().split() ().split () input split b c d e = hypot((a-c), (b-d)) e hypot((a-c), (b-d)) hypot a-c a c b-d b d print(e) print e a, b, c, d = map(float, input().split()) map(float, input().split()) a c, d = map(float, input().split()) map(float, input().split()) c b, c, d = map(float, input().split()) map(float, input().split()) b e = hypot((a-c), (b-d)) hypot((a-c), (b-d)) e d = map(float, input().split()) map(float, input().split()) d
from math import hypot

a, b, c, d = map(float, input().split())
e = hypot((a-c), (b-d))
print(e)